High cop absorption heat pumped evaporation method and apparatus

Abstract

A high efficiency open-cycle absorptive approach to compressing steam or other vapor is disclosed, especially useful for industrial evaportion via recompression. Referring to FIG. 1, low pressure steam from evaporator 1 is absorbed in an aqueous absorbent solution so as to release heat in both absorber 7 and GAX exchanger 8. External heat is applied to generator 12. Steam at higher pressure is desorbed from both gnerator 12 and GAX exchanger 8, and used to heat evaporator 1. Absorber 7 heat is also used to heat and evaporate the mixture undergoing evaporation.

What is claimed is: 
     
       1. Apparatus for increasing the pressure of water vapor from an initial pressure to a delivery pressure which is greater than the initial pressure by a factor of about 2 or less, using a quantity of heat which is no more than about 45% of the latent heat content of said water vapor, comprised of: (a) a generator;   (b) a means for supplying an aqueous absorbent solution to said generator;   (c) a means for supplying heat to said generator;   (d) a means for withdrawing water vapor at a pressure at least as high as the delivery pressure from said generator;   (e) a generator-absorber-heat-exchanger (GAX exchanger) having an absorption component and a desorption component which are in heat exchange relationship;   (f) a means for supplying part of said water vapor at the initial pressure to said GAX exchanger absorption component;   (g) a means for routing said aqueous absorbent solution from said generator to said GAX exchanger absorption component;   (h) a means for withdrawing water vapor at said delivery pressure from said GAX exchanger desorption component;   (i) an absorber;   (j) a means for supplying the remaining part of said water vapor at the initial pressure to said absorber;   (k) a means for routing said aqueous absorbent solution from said GAX exchanger absorption component to said absorber; and   (l) a pump for routing said aqueous absorbent solution from said absorber to the GAX exchanger desorption component.   
     
     
       2. Apparatus according to claim 1 additionally comprised of: (a) an evaporator;   (b) a means for feeding an aqueous feed mixture to said evaporator;   (c) a means for supplying said water vapor at the delivery pressure to said evaporator as heating medium therefor;   (d) a means for withdrawing the water vapor at the initial pressure from said evaporator and delivering it to said absorber and to said GAX exchanger; and   (e) a means for withdrawing concentrated aqueous feed mixture from said evaporator.   
     
     
       3. Apparatus according to claim 2 further comprised of a means for cooling said absorber by exchanging heat with at least part of said aqueous feed mixture. 
     
     
       4. Apparatus according to claim 3 including means for supplying said aqueous absorbent solution from said GAX exchanger desorption component to said generator. 
     
     
       5. Apparatus according to claim 1 additionally comprised of a second generator at about said initial pressure; a means for heating said second generator at least in part by condensing the high pressure water vapor withdrawn from said first generator; plus a second solution pump which transports aqueous absorbent solution from said second generator to said first generator. 
     
     
       6. Apparatus according to claim 1 additionally comprised of a means for heating said aqueous absorbent solution from said absorber. 
     
     
       7. Apparatus according to claim 1 wherein said aqueous absorbent solution is comprised of KNO 3 , NaNO 3  and H 2  O. 
     
     
       8. Apparatus according to claim 1 wherein said aqueous absorbent solution is comprised of water plus at least one component selected from the list comprised of alkali halides, alkali hydroxides, glycols, phosphoric acid, alkali thiocyanates, alkali nitrates, and alkali nitrites. 
     
     
       9. Apparatus according to claim 5 additionally comprised of a single-effect evaporator; a means for heating said single-effect evaporator by said water vapor at delivery pressure; and a means for withdrawing water vapor at said initial pressure from said single-effect evaporator. 
     
     
       10. An apparatus for compressing a vapor from an initial pressure to a delivery pressure which is higher than the initial pressure by a pressure ratio of no more than about four, comprised of: (a) a two-stage generator comprising a higher pressure stage and a lower pressure stage;   (b) a GAX exchanger composed of an absorption component and a desorption component;   (c) a means for supplying part of the vapor at the initial pressure to the absorption component of the GAX exchanger;   (d) a means for withdrawing part of the vapor at the delivery pressure from the desorption component of the GAX exchanger;   (e) a means for withdrawing the remaining part of the vapor at the delivery pressure from the lower pressure stage of the two-stage generator; and   (f) a means for heating the lower pressure stage of the two-stage generator by exchanging latent heat with vapor withdrawn from the higher pressure stage of the two-stage generator.   
     
     
       11. Apparatus according to claim 10 additionally comprised of an aqueous mixture evaporator which supplies the water vapor at the initial pressure to said GAX exchanger and receives the water vapor at the delivery pressure from both said lower pressure stage of the two-stage generator and said GAX exchanger. 
     
     
       12. A process for increasing the pressure of water vapor from an initial pressure to a delivery pressure which is higher than the initial pressure by a factor of about two or less, comprising: (a) absorbing part of said water vapor at the initial pressure in an aqueous absorbent solution to release a first quantity of heat;   (b) absorbing the remaining part of said water vapor at the initial pressure into said aqueous absorbent solution from part a), thereby releasing a second quantity of heat;   (c) raising the pressure of said aqueous absorbent solution from step b) to the delivery pressure, and applying said first quantity of heat to said pressurized aqueous absorbent solution thereby desorbing part of said water vapor at the delivery pressure; and   (d) heating said aqueous absorbent solution from step c) from an external source thereby desorbing a remaining part of said water vapor at the delivery pressure.   
     
     
       13. Process according to claim 12 additionally comprising using said steam at the delivery pressure for concentrating an aqueous mixture by evaporation; and withdrawing said steam at the initial pressure from said evaporation step.